Abstract
Offshore is a very corrosive environment with a high corrosion rate. The offshore coating service life is relatively short and extremely expensive to apply maintenance coatings onsite. It is offshore facility owners’ wish to select new construction and maintenance coatings lasting for 15 years or longer. The goal may be achieved by evaluation of the performance of candidate coatings in accelerated lab testing to identify qualified coatings. There are two international offshore coating standards – ISO 20340 and NACE SP0108 to guide the facility owners to select the qualified coating systems. Effective accelerated lab testing should simulate the failure modes in the field. The major failure modes of offshore atmospheric coatings are (1) rust creepage at scribes, (2) premature coating failure at sharp edges, corners, and weld seams, (3) thermal cycle cracking (4) aging embrittlement cracking. NACE has published five test standards for offshore coatings - NACE TM0104, 0204, 0304, 0404, and NACE SP0108 to qualify both new construction and maintenance coatings for atmospheric, splash zone, water ballast tank and water immersion areas. In addition to underfilm film corrosion testing, NACE standards also include coating physical testing, such as thermal cycling, edge retention and film flexibility, while ISO 20340 only test coating corrosion resistance. Their comparisons are discussed in this paper. A new accelerated coating corrosion test method is proposed.
